The present invention generally relates to apparatus and methods for ensuring that products being conveyed in nested patterns do not include holes in the nested pattern.
Products are often packaged in a grid pattern inside of a film overwrap or a corrugated wrap for shipping, handling and storage. Of course, if one or more of the products are missing when the film overwrap or corrugated wrap is sealed, this creates a defective package which is disadvantageous to the manufacturer of the products for several reasons. Products are loaded into the package by machines, with minimal labor involved such that detection of incomplete cartons is difficult, and if detected, would require stopping operation for correction which is often extremely disruptive to the packaging operation and even impossible.
In a typical packaging operation, product comes to a packaging machine in a continuous stream. It is necessary to separate product into groups so that they can be further processed such as being placed into a pack pattern and/or packed into the film overwrap or the corrugated wrap. U.S. Pat. Nos. 4,832,178 and 5,201,823 represent one manner of metering product utilizing pins which are inserted between product in lanes. However, such pin metering apparatus includes pins, rails, and supports between each lane of product which are multiple, high wear, moveable components and are very difficult and expensive to change over between different products. Other metering designs which control product from the side or top also require many parts, are complex, and are difficult to adjust.
In other packaging operations, products come to a packaging machine in a continuous stream of a plurality of products in a nested pattern which are then arranged into a grid pattern which is separated from the continuous stream of products. U.S. Pat. No. 6,793,064 and U.S. Publication Nos. 2003/0183484 and 2003/0234156 represent one manner of metering patterned products. It is believed that such methods are advantageous over lane type metering due to increased operational speeds, reduced machine complexity, increased machine life, reduced machine maintenance and the like. However, metering products from patterns are more prone to missing products (or holes) in the pattern of the continuous stream of products.
Thus, a need has arisen for methods and apparatus for removing holes in the pattern of nested products to ensure that when the patterned products are being metered that the pattern is complete and specifically that products are not missing from the pattern.